The present invention relates to a continuous high-pressure processing method and apparatus. More particularly, the present invention relates to a novel improvement in a method and apparatus for continuously processing, under high pressure, a liquid feedstock having a relatively high viscosity, such as foods, pharmaceuticals and cosmetics made up of oil-and-fat compositions, etc.
Such a high-pressure processing method has so far been practiced by batch processing, continuous processing using a throttle, continuous processing using a long or thin pipe to generate flow resistance. The continuous processing method using a throttle will be described below with reference to FIG. 13. FIG. 13 is a block diagram showing one example of conventional continuous high-pressure processing apparatus. In FIG. 13, the continuous high-pressure processing apparatus comprises a supply tank 9, a pressurizing pump 1, a processing container 6 provided with a built-in agitator, and a throttle 30, which are arranged successively in this order from the upstream end and are interconnected by pipes (piping) 5. A pressure gauge 2 and a safety valve 12 are disposed in the pipe 5 between the pressurizing pump 1 and the processing container 6. Further, a ripening apparatus 14 is disposed at the downstream end of the continuous high-pressure processing apparatus, i.e., downstream of the throttle 30.
In the continuous high-pressure processing apparatus having the above-described construction, a feedstock (comprising plural kinds of raw materials) 25 is introduced to the supply tank 9 where the raw materials are mixed under agitation for homogenization. The feedstock 25 in the supply tank 9 is sucked by the pressurizing pump 1 and delivered to the processing container 6 under pressure. In the processing container 6, the feedstock 25 is agitated while being maintained in the state pressurized to a predetermined level of high pressure, whereby the feedstock is subjected to processing such as sterilization and pressure crystallization. The feedstock 25 resides in the processing container 6 for a predetermined period of time so that it is uniformly processed under high pressure, and is then continuously discharged into the ripening apparatus 14 through the throttle 30. The pressure in the processing container 6 is maintained by both the pressurizing pump 1 and the throttle 30 for throttling a flow in the pipe 5 downstream of the processing container 6, and its measured value is indicated by the pressure gauge 2. The pressure in the processing container 6 and the residing time of the feedstock 25 are maintained at respective predetermined values by adjustably controlling the opening degree of the throttle 30, the rotational speed of the pressurizing pump 1, or both of them at the same time. If the pressure in the piping between the pressurizing pump 1 and the throttle 20 is increased to an abnormal level, the safety valve 12 is operated to release an abnormally excessive pressure.
The conventional processing methods mentioned above have problems as follows.
The batch processing has low productivity, has poor efficiency, and is difficult to implement as processing in an enclosed system.
Also, the batch processing entails works to be carried out in a manner open to the environment, and therefore has a difficulty in hygienic management in manufacture of foods and pharmaceuticals.
In the continuous processing method employing a throttle to hold the high-pressure state, a large amount of shearing energy is produced in a portion where a flow is throttled, thus causing dispersion of a flowing material under processing, which leads to destruction and change of components of the flowing material. As a result, liquid products obtained by the high-pressure processing are often no longer usable.
Further, in the continuous processing method using a thin or long pipe to produce flow resistance, when physical properties (compositions) of a flowing material (semi-liquid material) are changeable, it is difficult to make control so as to achieve a target pressure because viscosity is greatly changed depending on temperature changes. This method is also impractical in that a flow passage is clogged upon a slight change in components of the liquid material or operating conditions.
Another problem is that since driving power of a high-pressure pump, i.e., high-pressure flow energy, is changed into velocity energy at the throttle or thermal energy due to line resistance, greater driving power is required and hence the operating cost is increased.
With the view of overcoming the above-described problems in the state of the art, it is an object of the present invention to provide a continuous high-pressure processing method and apparatus, which are able to continuously perform high-pressure processing of a liquid feedstock with stability.
To achieve the above object, according to one aspect of the present invention, a continuous high-pressure processing method comprises the steps of supplying a feedstock continuously from a supply tank to a processing container through a pressurizing pump; discharging the processed feedstock from the processing container through a depressurizing pump disposed in piping; and setting a first delivery rate of the pressurizing pump to be larger than a second delivery rate of the depressurizing pump, whereby the interiors of the processing container and the piping are maintained in a high-pressure state.
Preferably, the method further comprises the step of coupling drive shafts of the pressurizing pump and the depressurizing pump to each other in a mechanically or electrically controllable manner.
Preferably, the method further comprises the steps of connecting the pressurizing pump and the depressurizing pump to a main drive motor and a driving distributor, providing a speed regulator in one downstream branch from the driving distributor, and setting a first driving speed of the pressurizing pump to be higher than a second driving speed of the depressurizing pump.
Preferably, the method further comprises the steps of connecting the pressurizing pump and the depressurizing pump to a main drive motor and a driving distributor, providing an auxiliary pressurizing pump, which has a smaller delivery rate than the pressurizing pump, in parallel to the pressurizing pump, and connecting a delivery portion of the auxiliary pressurizing pump to the outlet side of the pressurizing pump.
Preferably, the method further comprises the steps of connecting the pressurizing pump and the depressurizing pump to one main drive motor in series, providing an auxiliary pressurizing pump, which has a smaller delivery rate than the pressurizing pump, in association with the pressurizing pump, and connecting a delivery portion of the auxiliary pressurizing pump to the outlet side of the pressurizing pump.
Preferably, the method further comprises the steps of attaching a pressure sensor to the piping, and controlling the high-pressure state in accordance with a pressure signal from the pressure sensor.
Preferably, the method further comprises the steps of connecting the pressurizing pump and the depressurizing pump to one main drive motor through a driving distributor, and constituting any of the pressurizing pump and the depressurizing pump to be of the variable displacement type.
Preferably, the method further comprises the steps of connecting the pressurizing pump to one main drive motor through a driving distributor, connecting any of the depressurizing pump and the pressurizing pump to the driving distributor through a gear box, and setting a gear ratio of the gear box such that delivery rates of both the pumps are in match with each other.
Preferably, the method further comprises the steps of driving the pressurizing pump by a main drive motor, driving the depressurizing pump by a second motor independent of the main drive motor, and supplying power from the second motor, as electrical energy, to the main drive motor.
Preferably, the method further comprises the step of heating or cooling the processing container.
Preferably, in the method, the feedstock is any of foods and pharmaceuticals.
Also, a continuous high-pressure processing apparatus comprises a pressurizing pump for supplying a feedstock continuously from a supply tank to a processing container; a depressurizing pump disposed in piping downstream of the processing container; and a control unit for controlling delivery rates of both the pumps, the control unit controlling a first delivery rate of the pressurizing pump to be larger than a second delivery rate of the depressurizing pump.
Preferably, the control means comprises a driving distributor connected between both the pumps and a main drive motor, and a speed regulating motor connected to the driving distributor.
Preferably, the control means comprises a driving distributor connected between the pressurizing pump and a main drive motor, the depressurizing pump being connected to the driving distributor, and an auxiliary pressurizing pump connected in parallel to the pressurizing pump and having a smaller delivery rate than the pressurizing pump, a delivery portion of the auxiliary pressurizing pump being connected to the outlet side of the pressurizing pump.
Preferably, the pressurizing pump and the depressurizing pump are connected in series to the main drive motor, and the control means comprises an auxiliary pressurizing pump connected in parallel to the pressurizing pump, a delivery portion of the auxiliary pressurizing pump being connected to the outlet side of the pressurizing pump.
Preferably, the control means comprises a driving distributor for connecting the pressurizing pump and the depressurizing pump to a main drive motor, any of the pumps being of the variable displacement type.
Preferably, the control means comprises a second motor for driving the depressurizing pump, the second motor being independent of a main drive motor for driving the pressurizing pump, and a control line for supplying power from the second motor, as electrical energy, to the main drive motor.
Preferably, the processing container includes a heating unit and/or a cooling unit.
Preferably, the apparatus further comprises a pressure sensor attached to the piping.
Further, the method preferably further comprises the steps of attaching a plurality of pressure sensors to the piping, and employing a pressure signal from any of the pressure sensors.
Preferably, the method further comprises the steps of driving the pressurizing pump by a main drive motor, driving the depressurizing pump by a second motor independent of the main drive motor, and recovering power from the second motor as electrical energy or saving the power for economy of energy.
Preferably, the method further comprises the step of providing a throttle valve and/or a line resistance in part of the piping, thereby reducing a load imposed on the depressurizing pump.
Still further, in the apparatus, the control means preferably comprises a second motor for driving the depressurizing pump, the second motor being independent of a main drive motor for driving the pressurizing pump, and a control line and an amplifier for recovering power from the second motor as electrical energy or saving the power for economy of energy.
According to a second aspect of the present invention, a continuous high-pressure processing method comprises the steps of pressurizing a feedstock in a supply tank by a pressurizing pump and supplying the feedstock continuously to a processing container; discharging the processed feedstock continuously from the processing container through a flow resistance under depressurization, the flow resistance being able to adjust pressure; and providing a pressure-release bypassing circuit in parallel to the flow resistance, whereby the interior of the processing container is maintained in a state under a predetermined high pressure for continuous processing therein.
Preferably, the method further comprises the step of adjusting a temperature of the processing container to heat or cool the feedstock in the processing container.
Preferably, the method further comprises the step of cooling the processed feedstock in a cooling container downstream of the flow resistance.
Preferably, the method further comprises the steps of providing a plurality of processing containers connected to each other in series, and providing the flow resistance and the pressure-release bypassing circuit between the processing containers, whereby the interiors of the processing containers are maintained in states under high pressures changing step by step.
Preferably, the method further comprises the steps of providing the flow resistance in the form of a line designed to have a specific pipe length and/or pipe diameter, and switching on/off a plurality of valves disposed in the line to change the length of the line for changing a resistance value, whereby the interior of the processing container is maintained in a state under the predetermined high pressure.
Preferably, in the method, the flow resistance is constituted as a throttle valve.
Preferably, the method further comprises the step of controlling a resistance value of the flow resistance in accordance with a pressure signal from a pressure sensor attached to the processing container or a piping connected to the processing container, whereby the interior of the processing container is maintained in a state under a predetermined high pressure.
Moreover, a continuous high-pressure processing apparatus comprises a supply tank for storing a feedstock and agitating the feedstock therein for homogenization; a pressurizing pump for sucking the feedstock in the supply pump and supplying the sucked feedstock continuously to a processing container under pressure; the processing container for holding the feedstock to reside therein in a high-pressure state for a predetermined period of time while the feedstock is agitated for homogenization; a flow resistance for discharging the processed feedstock continuously from the processing container under depressurization, the flow resistance being able to adjust pressure; a pressure-release bypassing circuit provided in parallel to the flow resistance; and piping connected to the processing container, whereby the interior of the processing container is maintained in a state under a predetermined high pressure for continuous processing therein.
Preferably, the processing container has the temperature adjusting function to heat or cool the feedstock in the processing container.
Preferably, the apparatus further comprises a cooling container downstream of the flow resistance to cool the processed feedstock.
Preferably, in the apparatus, a plurality of processing containers are connected to each other in series, and the flow resistance and the pressure-release bypassing circuit are provided between the processing containers, whereby the interiors of the processing containers are maintained in states under high pressures changing step by step.
Preferably, the flow resistance comprises a line designed to have a specific pipe length and/or pipe diameter, and a plurality of valves disposed in the line, the valves being switched on/off to change a resistance value, whereby the interior of the processing container is maintained in a state under a predetermined high pressure.
Preferably, in the apparatus, the flow resistance is constituted as a throttle valve.
Preferably, the apparatus further comprises a pressure sensor attached to the processing container or a piping connected to the processing container, a resistance value of the flow resistance being controlled in accordance with a pressure signal from the pressure sensor, whereby the interior of the processing container is maintained in a state under a predetermined high pressure.